The present invention relates to an actuator for an inhaler for administering medicament by inhalation and to an inhaler, particularly a breath-actuated inhaler, including the same.
Breath-actuated inhalers are well known for delivering metered doses of medicament from aerosol canisters of the kind which comprise a body which defines a chamber containing medicament in a propellant under pressure, a valve stem which extends axially from one end of the body and an internal metering valve which is normally biased to a closed position and opened to deliver a metered dose of medicament when the valve stem is depressed. Such inhalers include a locking mechanism for selectively locking a canister in a non-actuated position and a loading mechanism for loading the canister with an actuation force, with the locking mechanism being released on inhalation by a user such that the loading mechanism actuates the canister to deliver a metered dose of medicament.
Examples of known breath-actuated inhalers are disclosed in U.S. Pat. No. 4,648,393, U.S. Pat. No. 5,060,643, U.S. Pat. No. 5,119,806 and WO-A-94/19040. U.S. Pat. No. 4,648,393 discloses an inhaler in which a biasing element for actuating a canister is loaded by pulling on one end of a lever arm. U.S. Pat. No. 5,060,643 discloses an inhaler in which a biasing element for actuating a canister is loaded by acting on a cap which is displaceable along the longitudinal axis of the canister. U.S. Pat. No. 5,119,806 discloses an inhaler in which a biasing element for actuating a canister is loaded by pulling on a strap. WO-A-94/19040 discloses an inhaler in which a biasing element for actuating a canister is loaded in lifting part of the casing so as to expose the mouthpiece.
It is an aim of the present invention to provide an actuator for an inhaler for administering medicament by inhalation which can be loaded in a quick and easy manner.
Accordingly, the present invention provides an actuator for an inhaler for delivering medicament by inhalation, comprising: a housing which defines a cavity for receiving a canister which comprises a body which defines a chamber containing medicament and a valve stem which extends from the body, the body and the valve stem of the canister being relatively movable between a first, non-actuated position in which the canister is closed and a second, actuated position in which the canister is open; a nozzle block for receiving the valve stem of the canister; a mouthpiece for providing medicament from the nozzle block to the mouth of a user, a locking mechanism for selectively locking the canister in the non-actuated position, which locking mechanism when released allows for the actuation of the canister; and a loading mechanism which comprises a biasing element for loading one of the body or the valve stem of the canister with an actuating force for to actuating the same and a lever arm which is pivotally coupled to the housing for loading the biasing element when rotated in one sense, which lever arm is configured so as to be rotated in the one sense on the manual application of opposed forces substantially orthogonal to the longitudinal axis of the canister.
Preferably, the loading mechanism further comprises a drawbar which is movably disposed relative to the pivot of the lever arm and coupled to the biasing element such that the drawbar is loaded as the biasing element is loaded, which drawbar includes at least one catch through which the biasing element is coupled to the one of the body or the valve stem of the canister.
More preferably, the biasing element is coupled to the lever arm at a point spaced from the pivot thereof.
Preferably, the pivot of the lever arm comprises a hinge pin and the drawbar includes at least one elongate slot through which the hinge pin extends such that the drawbar is moveably disposed to the housing between a first position and a second, extended position.
More preferably, the loading mechanism further comprises a support member which is pivotally coupled to the drawbar and pivotally and slideably coupled to the lever arm such that the drawbar is moved to the extended position when the lever arm is rotated in the other sense.
Yet more preferably, the drawbar includes a projection which is configured to engage the canister when rotated in the other sense so as to draw the canister at least partially from the cavity defined by the housing.
Preferably, the locking mechanism comprises a movable flap member which is configured to move on inhalation by a user through the mouthpiece and a link assembly which is operably coupled to the flap member such as to be released from a locking position in which the canister is locked in the non-actuated position on movement of the flap member.
More preferably, the link assembly comprises a first link which is pivotally coupled to the housing and includes an engagement surface which, in the locking position, is configured to prevent relative movement of the body and the valve stem of the canister, a second link which is pivotally coupled to the first link and operably coupled to the flap member and a biasing element for biasing the first link to the locking position.
Yet more preferably, when the first link is in the locking position, the engagement surface of the first link extends into the cavity defined by the housing such as to be engageable by the canister.
Preferably, when the first link is in the locking position, the engagement surface of the first link extends substantially orthogonally to the longitudinal axis of the canister.
Preferably, the first link and the housing are configured such that the first link cannot be rotated beyond the locking position under the action of the biasing element.
Preferably, the first link further includes a further engagement surface which is configured to engage a surface of the canister when in the actuated position and hold the first link in a displaced position.
Preferably, the flap member includes an axle and the second link includes a catch surface which is configured to engage the axle in the locking position and be disengaged therefrom on movement of the flap member by inhalation.
More preferably, the second link includes an engagement surface and the flap member includes a lever member, which engagement surface and lever member are configured such that, on movement of the flap member by inhalation, the lever member engages the engagement surface such as to move the second link and disengage the catch surface thereof from the axle of the flap member.
Yet more preferably, the engagement surface of the second link and the lever member are further configured such that the flap member is disposed in the closed position when the locking mechanism is in the locking position.
Preferably, the second link includes a further engagement surface which together with the lever member of the flap member is configured to hold the flap member in the open position when the locking assembly is in the displaced position.
Preferably, the actuator further comprises a casing which comprises first and second casing parts which are pivotally coupled between a first, closed position and a second, open position.
More preferably, the housing is fixed to one of the first and second casing parts and the other of the first and second casing parts is configured, on movement of the first and second casing parts between the closed and open positions, to rotate the lever arm in the one sense such as to load the biasing element.
Yet more preferably, the other of the first and second casing parts includes an opening through which the mouthpiece extends in the open position of the casing parts.
Preferably, the casing further comprises a latch for holding the casing parts in the open position.
Preferably, the pivot of the lever arm is substantially orthogonal to the longitudinal axis of the canister.
Such an actuator advantageously provides that the loading mechanism can be loaded in a single-handed operation without requiring any re-positioning of the hand in picking up the inhaler and bringing the same to the mouth. Indeed, the actuator is such as not to require any particular dexterity on the part of the user and can be operated, for example, by a user with limited hand function or when wearing gloves.
The present invention also provides an inhaler comprising the above-described actuator and a canister containing medicament.